Recent models of information processing emphasize the parallel and continuous nature of the system that evaluates and responds to external stimuli. Given the intricacy of this system, we propose the use of a multivariate approach in its analysis. Thus, we will integrate traditional measures of overt behavior with a series of psychophysiological measures (the event-related brain potential and the electromyogram) to map intermediate levels of processing. In fact, the development of new measures and analytic techniques to identify specific aspects of the information processing system will be an integral part of the proposed research. Our previous experiments on the processing of visual information has identified three mechanisms responsible for the latency and accuracy of overt behavioral responses: (a) a mechanism dependent on all the features present in the stimulus (feature analysis); (b) a mechanism dependent only on target information (location analysis); and (c) a mechanism independent of the stimulus information (aspecific priming). The experiments proposed will be designed to (a) analyze in detail the nature and time course of the mechanisms we have identified, (b) determine their interdependence and the nature of their interactions, and (c) integrate our observations with contemporary models of information processing.